生态脆弱区农村居民点布局优化对区域生态系统服务功能的影响——以四川省西昌市为例

我国是世界上生态脆弱区分布面积最大、类型最多、脆弱性表现最明显的国家之一。农村居民点作为生态脆弱区中主要人类活动区，成为导致生态脆弱区生态环境质量下降的重要干扰源。以四川省西昌市为例，分别利用InVEST模型中的生境质量评估模块、沉积物持留率分析模块、养分输出率分析模块评估了生态脆弱区农村居民点布局优化对区域生态系统服务功能的影响。研究结果表明：西昌市通过农村居民点布局优化，生境质量平均得分提高22.4%，土壤输出量下降4.6%，氮(N)、磷(P)输出量下降13.1%与8.2%，所以农村居民点布局优化有利于生态环境脆弱区生态系统服务功能的提升。农村居民点布局优化后，农村居民点数量与面积的减少，降低了森林火灾、土地开垦等植被破坏事件发生的频次，成为促使西昌市生境质量提升的主要原因；而农村居民点与农田面积下降，林地面积的增加是导致西昌市土壤输出量与N、P输出量下降的主要原因。农村居民点数量减少，可降低垃圾回收成本与污水处理成本，从而促使 N、P输出量进一步下降。

Impact of layout optimization of rural settlements in ecologically fragile areas on the regional ecosystem service function:a case study of Xichang City, Sichuan Province

China is one of the countries with the largest distribution area, the most types and the most obvious vulnerability of ecologically fragile areas in the world. As the main human activity area in the ecologically fragile area, the rural settlements have become an important source of interference that leads to the deterioration of the ecological environment. In this study, taking Xichang City, Sichuan Province as an example, the habitat quality model, sediment delivery ratio model, and nutrient delivery ratio model were used to evaluate the impact of layout optimization of rural settlements on the regional habitat quality, soil output and N-P output. The results indicate that the average score of habitat quality increased by 22.4%, soil output decreased by 4.6%, and N-P output decreased by 13.1% and 8.2% after layout optimization of rural settlements in the Xichang City. Therefore, layout optimization of rural settlements is beneficial to the improvement of the ecosystem service function in the Xichang City. After the layout optimization of rural settlements, the reduction in the number and area of rural settlements reduced the probability of forest fires, land reclamation and other vegetation destruction events, which become the main reason for the improvement of habitat quality. The decline in the area of rural settlements and farmland, and the increase in the area of woodland are the main reasons for the decline in soil output and N-P output. The decrease in the number of rural settlements will gradually reduce the cost of waste recycling and sewage treatment in rural areas, thereby further reducing the output of N-P.